Carbon from the fires of Manchester and Chesterfield covered Derbyshire’s famous Chatsworth house in black grime. But after a year’s work specialist stone restorers and masons have cleaned all the muck away and the house now looks very much like it would have done when it was remodelled over 200 years ago. Restoration is big business. It cost £14m to restore the 300-year-old Chatsworth House in Derbyshire to its former glory, and the work is on-going with teams of skilled craftsman continuing regular maintenance.

Chatsworth was getting a reputation for being a grubby stately home, but it wasn’t the fault of the Duke of Devonshire more the black sooty carbon that masked the beautiful yellow honey coloured stone that blew in from the coal fires that heated nearby Manchester and Chesterfield. A build-up of sooty air-borne carbon over a period of 200 years had taken the ‘glow’ off the magnificent house remodelled by the 6th Duke of Devonshire in the 1820’s. The comments of a visitor from Toronto, Canada summed up the problem with Chatsworth when he saw it for the first time: “It looks like a dirty prison,” he said, “it could do with a good clean.”

The present day Duke was obviously on the case because he and his team set about pulling together a £14m Masterplan that was to see a large part of the highly-decorated building restored to how it probably looked when it was originally built. It has been a huge undertaking because not only did 2,200 square metres of blackened sandstone need cleaning, but weather-worn areas of stone had to be replaced as well. Ironically all the new stone used in the repairs came from the same quarry that supplied the original stone when the house was remodelled 200-years earlier.

Chemically cleaning the blackened stone had to be done with care and caution. The big clean up began with the stone being softened with a salt solution, then it was steam cleaned, and finally a very weak acid solution was applied to ease the grime away from the stone. With both south and west fronts fully restored plans are now in hand to tackle the east front, which visitors can see from the garden.

But it wasn’t just the stone that got a makeover, carvings were repaired, 42 window frames were re-gilded, and the 21 two-foot high urns positioned at the very top of the house have been restored as well. No one team could carry out all this specialist work, which is why half a dozen consultancies became involved along with contractors, project managers and archaeologists.

But the key part of the cleaning team were a Yorkshire stone carver and 12 stonemasons who carried out all the expert restoration work over a 56-week rolling programme much of it hidden behind scaffolding and protective sheeting. Work not only involved cleaning the stone but also repointing the 20-metre high facades with over a tonne of lime mortar, the bonding material that would have been used on the original house.

Sean Doxey, Chatsworth’s head of special projects said: “It was felt the work needed doing now, because although the building was in pretty good condition, it would have started to deteriorate due to weather and air pollution damage”. Sean and his team didn’t work blind on the project because the house records contained lots of vital information, including plans, details and original invoices, which gave the restorers clues on where to source all sorts of materials, including gold leaf.

The Duke and Duchess of Devonshire said: “The restoration was put in hand to protect Chatsworth’s heritage, and it is absolutely wonderful to now look at the house and see it appear how our ancestors would have viewed it. With the years of grime removed the house now looks magical again, and we are also pleased that it has been preserved for future generations to see and enjoy”.